From 05ea9ea585baca72ff80326713a31352bc748f83 Mon Sep 17 00:00:00 2001
From: Sterling Harper <smharper@mit.edu>
Date: Sat, 17 Oct 2020 20:34:41 -0600
Subject: [PATCH] Move reflective/white BCs to a new class

---
 CMakeLists.txt             |  1 +
 include/openmc/particle.h  |  2 +-
 include/openmc/surface.h   |  2 ++
 src/boundary_condition.cpp | 29 +++++++++++++++++++++++++++++
 src/particle.cpp           | 14 ++++----------
 src/surface.cpp            |  2 ++
 6 files changed, 39 insertions(+), 11 deletions(-)
 create mode 100644 src/boundary_condition.cpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index a59e6f7e3a..5e99b6151e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -225,6 +225,7 @@ target_compile_options(faddeeva PRIVATE ${cxxflags})
 
 list(APPEND libopenmc_SOURCES
   src/bank.cpp
+  src/boundary_condition.cpp
   src/bremsstrahlung.cpp
   src/dagmc.cpp
   src/cell.cpp
diff --git a/include/openmc/particle.h b/include/openmc/particle.h
index 9168dd6e0a..48570c4ea9 100644
--- a/include/openmc/particle.h
+++ b/include/openmc/particle.h
@@ -244,7 +244,7 @@ public:
   void cross_vacuum_bc(const Surface& surf);
 
   //! Cross a reflective boundary condition.
-  void cross_reflective_bc(const Surface& surf);
+  void cross_reflective_bc(const Surface& surf, Direction new_u);
 
   //! Cross a periodic boundary condition.
   void cross_periodic_bc(const Surface& surf);
diff --git a/include/openmc/surface.h b/include/openmc/surface.h
index cef5f4f880..010d9dfa28 100644
--- a/include/openmc/surface.h
+++ b/include/openmc/surface.h
@@ -10,6 +10,7 @@
 #include "hdf5.h"
 #include "pugixml.hpp"
 
+#include "openmc/boundary_condition.h"
 #include "openmc/constants.h"
 #include "openmc/particle.h"
 #include "openmc/position.h"
@@ -95,6 +96,7 @@ public:
 
   int id_;                    //!< Unique ID
   BoundaryType bc_;                    //!< Boundary condition
+  std::shared_ptr<BoundaryCondition> new_bc_ {nullptr};
   std::string name_;          //!< User-defined name
 
   explicit Surface(pugi::xml_node surf_node);
diff --git a/src/boundary_condition.cpp b/src/boundary_condition.cpp
new file mode 100644
index 0000000000..d9c463ca09
--- /dev/null
+++ b/src/boundary_condition.cpp
@@ -0,0 +1,29 @@
+#include "openmc/boundary_condition.h"
+#include "openmc/surface.h"
+
+namespace openmc {
+
+void
+ReflectiveBC::handle_particle(Particle& p, const Surface& surf) const
+{
+  Direction u = surf.reflect(p.r(), p.u(), &p);
+  u /= u.norm();
+
+  p.cross_reflective_bc(surf, u);
+}
+
+void
+WhiteBC::handle_particle(Particle& p, const Surface& surf) const
+{
+  Direction u = surf.diffuse_reflect(p.r(), p.u(), p.current_seed());
+  u /= u.norm();
+
+  p.cross_reflective_bc(surf, u);
+}
+
+//void
+//PeriodicBC::handle_particle(Particle& p, const Surface& surf) const
+//{
+//}
+
+} // namespace openmc
diff --git a/src/particle.cpp b/src/particle.cpp
index 2097ba0da3..ba68ce2eb8 100644
--- a/src/particle.cpp
+++ b/src/particle.cpp
@@ -414,8 +414,6 @@ Particle::cross_surface()
   }
 
   if (surf->bc_ == Surface::BoundaryType::VACUUM && (settings::run_mode != RunMode::PLOTTING)) {
-    // =======================================================================
-    // PARTICLE LEAKS OUT OF PROBLEM
 
     cross_vacuum_bc(*surf);
 
@@ -425,7 +423,7 @@ Particle::cross_surface()
               surf->bc_ == Surface::BoundaryType::WHITE)
               && (settings::run_mode != RunMode::PLOTTING)) {
 
-    cross_reflective_bc(*surf);
+    surf->new_bc_->handle_particle(*this, *surf);
 
     return;
 
@@ -515,7 +513,7 @@ Particle::cross_vacuum_bc(const Surface& surf)
 }
 
 void
-Particle::cross_reflective_bc(const Surface& surf)
+Particle::cross_reflective_bc(const Surface& surf, Direction new_u)
 {
   // Do not handle reflective boundary conditions on lower universes
   if (n_coord_ != 1) {
@@ -542,12 +540,8 @@ Particle::cross_reflective_bc(const Surface& surf)
     this->r() = r;
   }
 
-  Direction u = (surf.bc_ == Surface::BoundaryType::REFLECT) ?
-    surf.reflect(this->r(), this->u(), this) :
-    surf.diffuse_reflect(this->r(), this->u(), this->current_seed());
-
-  // Make sure new particle direction is normalized
-  this->u() = u / u.norm();
+  // Set the new particle direction
+  this->u() = new_u;
 
   // Reassign particle's cell and surface
   coord_[0].cell = cell_last_[n_coord_last_ - 1];
diff --git a/src/surface.cpp b/src/surface.cpp
index f2faa3efee..6296e128b4 100644
--- a/src/surface.cpp
+++ b/src/surface.cpp
@@ -134,8 +134,10 @@ Surface::Surface(pugi::xml_node surf_node)
     } else if (surf_bc == "reflective" || surf_bc == "reflect"
                || surf_bc == "reflecting") {
       bc_ = BoundaryType::REFLECT;
+      new_bc_ = std::make_shared<ReflectiveBC>();
     } else if (surf_bc == "white") {
       bc_ = BoundaryType::WHITE;
+      new_bc_ = std::make_shared<WhiteBC>();
     } else if (surf_bc == "periodic") {
       bc_ = BoundaryType::PERIODIC;
     } else {